/Engine/Source/Runtime/Landscape/Classes/LandscapeProxy.h
Overwrites a landscape weightmap with render target data Only works in the editor
bool LandscapeImportWeightmapFromRenderTarget ( [UTextureRenderTarget2D](API\Runtime\Engine\Engine\UTextureRenderTarget2D) * InRenderTarget, [FName](API\Runtime\Core\UObject\FName) InLayerName )